1. Field of the Invention
The invention relates to a method for epoxidizing olefins and catalysts employed therefor.
2. The Related Art
A variety of manganese compounds have been known for activating oxidation of unsaturated bonds. GB 2 225 963A (Casson et al) describes a manganese porphyrin supported on an inorganic substrate. The composition was indicated as useful for epoxidation of aromatics such as styrene. DE 34 38 484 (Rohde) describes the combination of a transition metal, phthalocyanine, and iodosobenzene as a useful epoxidation reagent.
JP 60 197 664A (Tabuse) reports epoxidation of polyenes through contact with a metal porphyrin, imidazole compound, platinum and hydrogen. Various solvents including water are suggested as effective media.
A problem with the known art is that metallo-porphyrin and phthalocyanine compounds are not readily soluble in aqueous media. Homogeneous catalysis is, therefore, problematical. Even in systems wherein manganese complexes operate heterogeneously, there remains room for yield and conversion improvements.
Accordingly, it is an object of the present invention to provide novel catalysts and a method for epoxidation of olefins which may be conducted homogeneously.
A further object of the present invention is to provide novel catalysts and a method for epoxidation of olefins which achieves improved yields and conversion over known catalytic systems.
These and other objects of the present invention will become more readily apparent from the detailed description and examples given hereafter.